diff --git a/homeassistant/components/fritzbox_callmonitor/base.py b/homeassistant/components/fritzbox_callmonitor/base.py
index 0db40e2098f..6114e4b1fed 100644
--- a/homeassistant/components/fritzbox_callmonitor/base.py
+++ b/homeassistant/components/fritzbox_callmonitor/base.py
@@ -1,4 +1,6 @@
 """Base class for fritzbox_callmonitor entities."""
+from __future__ import annotations
+
 from contextlib import suppress
 from datetime import timedelta
 import logging
@@ -19,18 +21,26 @@ MIN_TIME_PHONEBOOK_UPDATE = timedelta(hours=6)
 class FritzBoxPhonebook:
     """This connects to a FritzBox router and downloads its phone book."""
 
-    def __init__(self, host, username, password, phonebook_id, prefixes):
+    fph: FritzPhonebook
+    phonebook_dict: dict[str, list[str]]
+    number_dict: dict[str, str]
+
+    def __init__(
+        self,
+        host: str,
+        username: str,
+        password: str,
+        phonebook_id: int | None = None,
+        prefixes: list[str] | None = None,
+    ) -> None:
         """Initialize the class."""
         self.host = host
         self.username = username
         self.password = password
         self.phonebook_id = phonebook_id
-        self.phonebook_dict = None
-        self.number_dict = None
         self.prefixes = prefixes
-        self.fph = None
 
-    def init_phonebook(self):
+    def init_phonebook(self) -> None:
         """Establish a connection to the FRITZ!Box and check if phonebook_id is valid."""
         self.fph = FritzPhonebook(
             address=self.host,
@@ -40,7 +50,7 @@ class FritzBoxPhonebook:
         self.update_phonebook()
 
     @Throttle(MIN_TIME_PHONEBOOK_UPDATE)
-    def update_phonebook(self):
+    def update_phonebook(self) -> None:
         """Update the phone book dictionary."""
         if self.phonebook_id is None:
             return
@@ -53,17 +63,15 @@ class FritzBoxPhonebook:
         }
         _LOGGER.info("Fritz!Box phone book successfully updated")
 
-    def get_phonebook_ids(self):
+    def get_phonebook_ids(self) -> list[int]:
         """Return list of phonebook ids."""
         return self.fph.phonebook_ids
 
-    def get_name(self, number):
+    def get_name(self, number: str) -> str:
         """Return a name for a given phone number."""
         number = re.sub(REGEX_NUMBER, "", str(number))
-        if self.number_dict is None:
-            return UNKNOWN_NAME
 
-        if number in self.number_dict:
+        with suppress(KeyError):
             return self.number_dict[number]
 
         if not self.prefixes:
@@ -74,3 +82,5 @@ class FritzBoxPhonebook:
                 return self.number_dict[prefix + number]
             with suppress(KeyError):
                 return self.number_dict[prefix + number.lstrip("0")]
+
+        return UNKNOWN_NAME